Side-discharge melter for use in the manufacture of fiberglass

ABSTRACT

An electric open-top melter for use in the manufacture of mineral fibers, such as fiberglass, is provided with a side-discharge outlet. The side-discharge outlet allows the melter, conditioner/refiner, and forehearth to all be located on substantially the same level, thereby allowing molten glass to flow from the side of the melter, through the conditioning zone, and into the forehearth from which spinners produce glass fibers or the like. Isolation members are provided in the conditioning or refining area so as to enable molten glass therein to be isolated from the melter and forehearth when the molten glass level is lowered below the tops the isolation members.

This invention relates to a glass melter for use in the manufacture offiberglass, and corresponding method. More particularly, this inventionrelates to an outlet structure for a side-discharge glass melter for usein the manufacture of fiberglass, and corresponding method, wherein theside-discharge outlet extends the melter's continuous operation time,thereby improving production efficiency.

BACKGROUND OF THE INVENTION

Glass melters, or furnaces, for use in the manufacture of glass fibers,are old and well-known throughout the art. For example, see U.S. Pat.Nos. 4,017,294 and 4,023,950.

The '294 patent generally describes an open-top electric melter, orfurnace, having a central bottom discharge outlet. The melter includes aceramic lining and a molybdenum outlet member located at the bottom ofthe melter, at the center thereof. The tapping block of the outlet ismade of molybdenum, a material which is able to withstand hightemperatures within the furnace and is substantially corrosionresistant. Unfortunately, glass melters which include outlets located atthe bottom center of the melter, as in the '294 patent, have been foundto suffer from a number of problems, some of which are discussed below.

The bottom center of an electric open-top glass melter experiences thehighest temperatures in the melter (e.g. from about 3,100°-3,200° F. insome electric melters). The rate of corrosion of outlet structures istemperature related. Accordingly, due to oxides found in the glassbatch, molybdenum center outlets, such as that disclosed in the '294patent, tend to wear out quicker than do refractory linings provided onthe sidewalls and bottom of such furnaces. In such cases, because theoutlet needs to be replaced prior to the refractory lining material, thefurnace must be shut down for repairs more often. For example, assumingthat the refractory lining in such an electric melter needs to bereplaced approximately once a year, the molybdenum center outlet whichwears out at a more rapid rate would have to be replaced every sixmonths or so, thereby necessitating twice as many shutdowns of thefurnace than would be needed if the refractory and outlet structure woreout, and could be replaced, at the same time. Each time a melter in afiberglass manufacturing plant is shut down in order to replace eitherthe outlet structure or the refractory lining, production and outputsuffer. This is undesirable.

U.S. Pat. No. 4,001,001 discloses a combination gas and electric furnacethat is horizontal in design (i.e. the melter and refiner are atsubstantially the same level) and adapted for melting glass batchmaterials in part by the application of heat from overhead flames withinthe furnace. This furnace includes electric heating electrodes submergedwithin the batch material and gas fueled flame firing ports located inthe atmosphere at an elevation above the batch. The atmosphere above thebatch is heated by these flames so that the entire glass batch,including the top surface of the batch, within the melter is melted intomolten form (i.e. no hardened or quasi-solid glass batch is present onthe top surface of the batch as it flows into the refiner).

Unfortunately, the melter of the '001 patent suffers from a number ofproblems, some of which are set forth below. The melter of the '001patent is a combination gas-electric melter, including a closed-top(i.e. hot-top) which keeps the atmosphere within the melter, above theglass batch, at a heightened temperature in order to melt the glass onthe top surface of the batch. These types of melters are often viewed asinefficient with regard to energy consumption. Furthermore, this type ofmelter requires that the top surface of the glass batch be in moltenform prior to entry into the refiner so that the spinners do not becomeclogged (i.e. there is no structure to prohibit entry of quasi-hardenedbatch on the top surface from flowing into the refiner). The atmosphereheating requirement is undesirable, very costly, and inefficient. Stillfurther, the furnace of the '001 patent does not typically heat thebatch to the extreme temperatures of electric open-top melters, and thusdoes not typically need to address the same degree of erosion problemsassociated with high temperature electric open-top melters.

U.S. Pat. No. 4,405,351 discloses another hot-top, or closed-top,gas-fueled melter or furnace used in the manufacture of glass fibers.Unfortunately, the melter of the '351 patent suffers from at least thesame problems discussed above relative to the '001 patent, in that: (i)its low operating temperatures (up to 2,600° F.) do not render itsusceptible to the erosion problems associated with the much higherbatch temperatures of electric open-top furnaces; (ii) the fuel-airmethod of heating and melting the batch in the '351 patent is ofteninefficient and undesirable; and (iii) the throat or side outlet throughwhich the molten glass flows into the refiner would erode much tooquickly if exposed to the higher temperatures of electric furnaces. Forexample, if the throat (typically made of refractory material which canwithstand the heat generated in a gas furnace) in the '351 patent wasexposed to temperatures on the order of from about 2,700°-3,200° F., itwould break down/erode, especially upwardly, due to "upward drilling" ofthe throat. However, because the temperatures maintained within thebatch in the gas melter of the '351 patent are so low, this problem isnot addressed therein.

In view of the above, it is readily apparent that there exists a need inthe art for an electric open-top glass melter, and corresponding method,for use in the manufacture of glass fibers wherein the melter isprovided with an outlet or throat structure that wears out at a slowerrate than do prior art outlets which are located at the bottom center ofthe melter, and which prevents solid or quasi-solid glass batch anderoded refractory from flowing from the melter interior toward theforehearth. Still further, there exists a need in the art for a melterthat has reduced downtime (i.e. an increase in production results).

It is a purpose of this invention to fulfill the above-described needsin the art, as well as other needs which will become apparent to theskilled artisan from the following detailed description of thisinvention.

SUMMARY OF THE INVENTION

Generally speaking, this invention fulfills the above-described needs inthe art by providing an open-top electric melter system for use in theforming of glass fibers, the open-top electric melter system comprising:

a melter including a water cooled melter shell with an interior area forholding glass material therein, the shell having an open-top so that theatmosphere above the glass material is not heated other than by way ofheat emitted from glass in the melter;

electrical heating means for heating the glass material in the melter sothat a substantial portion of the glass material in the melter is inheated molten form and a top surface of the glass material in the melteris substantially unmelted and in quasi-solid or solid form;

a side-discharge outlet located at a side of the melter, the outletpermitting molten glass from within the melter to flow out of the melterand into a conditioning area; and

wherein the side-discharge outlet includes an elongated metallic tubehaving a flow aperture defined therein through which the molten glassflows from the melter toward the conditioning or refining area, the flowaperture defining a top edge and a bottom edge and being located betweenthe interior of the melter and the conditioning area.

This invention also fulfills the above-described needs in the art byproviding a method of forming glass fibers by utilizing an open-topmelter, conditioning structure, and forehearth, the method comprisingthe steps of:

providing the melter, conditioning or refining structure, andforehearth;

loading glass materials to form glass, such as SiO₂, CaO, and the like,into the melter;

electrically heating the glass materials in the melter so as to cause asubstantial portion of the glass materials in the melter to transforminto molten form, with a top surface of the glass material in the melterremaining in solid or quasi-solid unmelted form due to the ambientatmosphere above the glass material in the open-top melter;

causing the molten glass to flow out of the melter by way of aside-discharge outlet defined therein, the side-discharge outletincluding a metallic tube surrounded by refractory material;

the molten glass flowing from the melter, through the discharge outlet,and into the conditioning or refining area or structure, and thereafterinto the forehearth after which glass fibers are formed.

In certain preferred embodiments, the side-discharge outlet is providedwith an elongated metallic (e.g. molybdenum) tube surrounded by bothrefractory material and a water cooling chamber.

In certain preferred embodiments, the conditioning or refining structureis provided with a pair of isolation members located at opposite endsthereof, the isolation members allowing molten glass between them to beisolated from both the melter and forehearth when the molten glass levelwithin the system is lowered to a level below the tops of the isolationmembers. This allows for more efficient maintenance to be performed onthe system.

This invention will now be described with reference to certainembodiments thereof and is illustrated in the following drawings.

IN THE DRAWINGS

FIG. 1 is a top plan view of a side-discharge glass melter according toan embodiment of this invention.

FIG. 2 is a side cross-sectional view of the melter of FIG. 1.

FIG. 3 is a top view of a side-discharge glass melter according toanother embodiment of this invention.

FIG. 4 is a side cross-sectional view of the FIG. 3 melter.

FIG. 5 is a side cross-sectional view of a side-discharge throatstructure which may be used in any of the above-described embodiments.

FIG. 6 is a top plan view of the FIG. 5 throat structure.

FIG. 7 is an end view of the throat structure of FIGS. 5-6.

FIG. 8 is a side cross-sectional view of a throat structure which may beused in any of the above-described embodiments, according to anotherembodiment of this invention.

FIG. 9 is an end view of the FIG. 8 throat.

FIG. 10 is a side cross-sectional view of a forehearth used in anyembodiment of this invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THIS INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numeral indicate like parts throughout the several views.

FIG. 1 is a top plan view illustrating an electric, open-top, glassmelter for use in the manufacture of glass fibers, according to anembodiment of this invention. As illustrated, melter 1 includes vessel 3having a water-cooled metallic (e.g. steel) outer shell 5 and arefractory sidewall and bottom lining 7, the melter or furnace 1 beingsupported on a conventional support structure which is not illustrated,in order to receive or house molten glass batch in its interior cavity15. The annular portion of the melter, defined within shell 3, housesthe molten glass, the top surface of which is typically unmelted orhardened batch (i.e. in solid or quasi-solid form) due to the relativelylower temperature of the ambient atmosphere located above the surface ofthe batch. Thus, the surface is typically unmelted batch which consistsessentially of a proportion blend of the various raw materials (e.g.SiO₂, B₂ O₃, C_(a) O, etc.) from which a glass is formed. The unmeltedbatch functions as both an insulation cover over top of the molten glasspool below, and a source of vitrifiable material in that it can bemelted.

Due to the heating power directed to the glass via glass meltingelectrodes 8 (see FIGS. 2 and 4), the molten glass within the melter istypically maintained at a temperature of about 3,150°-3,250° F. near thecenter of the melter and about 2,500°-2,700° F. near the sidewalls.Thus, the electric melter maintains the glass batch at temperatures offrom about 2,500°-3,250° F., (preferably from about 2,800°-3,250° F.)with the open or ambient atmosphere above the batch being ambienttemperature more than just a few feet away from the batch surface.

Referring to FIGS. 1-2, the melter includes a side-discharge outletstructure 9 located on one side or edge of the annular portion of themelter. Side-discharge outlet structure 9 includes metallic throatstructure 11 having elongated orifice 13 defined therein, which allowsmolten glass batch to flow from the interior 15 of vessel 3 intoconditioning or refining zone 17 where the glass is refined andvolatiles are driven or burned off, and sometimes recycled. For example,sodium borate vapors, which are corrosive, are burned off and/orrecycled to vessel 3, within conditioning zone 17.

While in conditioning zone 17, the glass batch is present within andflows through elongated chamber or channel 19. The molten glass flowsfrom the conditioning zone 17 and channel 19 into glass delivery area,or forehearth 21. Forehearth 21 includes equipment for forming glassfibers, such as burners 47, and conventional spinners or fiberizers.

FIG. 10 is a side partial cross-sectional view of a forehearth 21 usedin any embodiment of this invention, illustrating burners 47, channel22, and bushings 10. The molten glass flows along a channel 22 definedwithin forehearth 21 and is withdrawn through bushings 10 therebydropping 12 as molten glass streams into corresponding spinners. Moltenglass within the spinners is forced to flow through orifices in walls ofthe spinners by centrifugal force thereby forming the glass fibers asknown in the art. An exemplary spinner is illustrated, for example, inU.S. Pat. No. 4,737,178, the disclosure of which is incorporated hereinby reference.

Because central outlets or discharges in electric melters wear out at arather rapid rate, the side-discharge outlet structure 9, of thedifferent embodiments of this invention, is positioned and designed soas to wear out at a slower rate such that refractory 7 along with theoutlet structure 9 may be replaced or otherwise maintenancedsimultaneously during the same shutdown of the melter 1. This improvesproductivity and efficiency.

Because the glass batch within area or cavity 15 of vessel 3 is coolernearer sidewall 23 than it is proximate the center 25 of the melter, theoutlet structure 9 as positioned is less susceptible to corrosion andbreaking down, due to the fact that such corrosion is a function oftemperature (i.e. the higher the temperature, the quicker thecorrosion/breakdown of the outlet structure).

As can be seen in FIGS. 1-2, melter 1 including vessel 3, along with theconditioner structure of the conditioning zone 17 and forehearth 21 areall on substantially the same level (i.e. they are substantially planarrelative to one another). This is an important feature of certainembodiments of this invention, as it allows the mineral fiber or glassfiber manufacturing facility to save, or delete, an entire floor. Forexample, in typical fiberglass manufacturing facilities, (e.g. see U.S.Pat. No. 4,023,950, the disclosure of which is incorporated herein byreference), the melter is located above, and on a different elevation orlevel, than the forehearth due to the bottom outlet. Often, the melterwill be on one floor of a manufacturing facility, with the forehearthinto which the molten glass flows being located on another floor locatedat an elevation beneath the floor upon which the melter is provided. Thestructure according to certain embodiments of this invention, whereinthe melter 1, conditioning zone 17, and forehearth 21 are all located onthe same level, allows all of this to be located on the same floor,thereby eliminating the need for the additional floor which is oftenrequired in the prior art. Also, the use of prior art melter needles inthe center of the melter is eliminated no center orifice or needle isneeded! in this invention.

Outlet structure 9 may be varied according to different embodiments ofthis invention. However, referring to FIGS. 2 and 4, it is importantthat the bottom edge 27 of aperture 13 be located at an elevationsubstantially above (e.g. from about 2-6 inches above, and preferably atleast about 2 inches above) the bottom wall 29 of vessel 3 proximate theoutlet so that corroded refractory materials which have eroded from thebottom and sidewall areas of the melter and are located at the bottomthereof, cannot flow out of area 15 through throat orifice 13.Furthermore, it is also important that the top edge 31 of orifice 13 belocated at an elevation substantially below (e.g. from about 2-6 inchesbelow and preferably at least about 2.0 inches below) the top unmeltedbatch surface 33 of the glass batch within area 15. This is because, inan electric open-top melter such as those described according to theembodiments of this invention, the top surface 33 of the batch istypically hardened, or in solid or quasi-solid glass form due to theambient atmosphere above level 33 that is at substantially at an ambienttemperature. By locating the top edge 31 of throat orifice 13 at anelevation substantially below top batch surface 33, the structure 9prevents solid unmelted glass batch materials from flowing from vessel 3into conditioning zone 17 and forehearth 21 where it may clog or blockthe bushings 10 and/or spinner apertures the spinners have apertureswith diameters of from about 0.013-0.025 inches!. This is importantbecause, due to the lower temperatures within refining zone orconditioning zone 17, and forehearth 21, if solid glass batch were tomake its way thereinto, it may not melt thereby resulting in suchclogging.

As illustrated in FIGS. 1-4, metallic throat member 11 is annular orcylindrical in shape, and has defined therein cylindrical elongatedaperture 13 which allows area 15 within vessel 3 to communicate withpassageway 19 within the conditioning zone. Throat 11 is typically madeof molybdenum (Mo), which is resistant to corrosion at hightemperatures. According to certain embodiments, the diameter of annularaperture 13 may be approximately two inches (or from about 1.5 to 4.0inches) so that the molten glass throughput through throat aperture 13from area 15 into passageway 19 is approximately 6,000 lbs. per hour (orfrom about 5,000-7,000 lbs./hr.), and the velocity through aperture 13(when the inner diameter aperture of the orifice is from about 1.5-3.0inches) would be from about 13-28 feet per minute. When orifice 13 has adiameter of about 2", the velocity may be about 28 feet/min. in certainembodiments of this invention. The outer diameter of throat 11 may befrom about 4-7 inches. It is to be recognized that throat 11 need not becylindrical or annular, and may take on various shapes (e.g.rectangular) according to alternative embodiments of this invention. Incertain embodiments such as in FIGS. 3-4, throat member 11 may include amolybdenum elongated tube which defines aperture 13 therein, this tubebeing surrounded by refractory block thereby making up a multi-piecethroat member 11. Alternatively, throat member 11 may be made ofplatinum (Pt), or platinum clad refractory.

Throat 11 is of Mo, or the like, so that upward drilling, or erosion,thereof is prevented, thereby keeping solid batch from making its waytoward the forehearth.

Referring to FIGS. 1-2, conditioner or conditioning zone 17 of thisembodiment includes an elongated passageway 19 defined withinsurrounding structure 35. Conditioner structure 35 includes a watercooled floor panel 37, conditioner drain 39, passageway 19 connectingorifice 13 with forehearth 21 (the level or elevation of the moltenglass within the conditioner is illustrated by reference numeral 41),heating vent 43 (one provided) and finally cooling vents 45 (fourprovided). With regard to forehearth 21, the forehearth includes aplurality of burners 47 provided above the level 41 of the molten glass,and an encompassing forehearth structure 49 as is known in the art.Melter 1 further includes melter drain 51 that is defined within watercooled floor panel 53. Water cooled side panels 55 are also provided inorder to maintain a lower refractory temperature proximate the sidewallswithin area 15 and to extend the life of the refractory lining 7.

According to certain embodiments, the bottom edge 27 of throat orifice13 is located at an elevation of about six inches above floor 29 of themelter, and top edge 31 is located at an elevation approximately sixinches below the level 33 of the batch within the melter. Meanwhile,according to this embodiment, level 33 is maintained at an elevation ofapproximately sixteen inches above floor 29 proximate the center of themelter. Interior 15 of the melter may have a diameter of approximately12.5 feet according to certain embodiments, while throat structure 11may have a length, defined between the end adjacent area 15 and the endadjacent passageway 19, of approximately eighteen inches. According tocertain embodiments, the structure of conditioning zone 17 furtherincludes water cooled side panels 57, as illustrated in FIG. 1. Asillustrated, the bottom or floor 29 of the melter may be sloped downwardtoward the center from the side opposite the outlet.

FIGS. 3-4 illustrate a melter 1, and corresponding side-dischargestructure 9, according to another embodiment of this invention. Theapparatus of FIGS. 3-4 is similar to that of FIGS. 1-2, except that adifferent discharge or outlet structure 9 is provided. The dischargestructure 9 according to the FIG. 3-4 embodiment, includes elongatedthroat tube 11 (e.g. made of molybdenum) defining elongated passagewayor aperture 13 therein, three separate water cooled molybdenumelectrodes 61, a water cooled throat wall 63 (one such water cooled wallon each of the opposing two sides of the throat), and refractorymaterial 65 supporting and enveloping the molybdenum throat tube 11. Asillustrated, the refining zone 17 in this embodiment is shorter inlength than the zone 17 in the FIG. 1-2 embodiment.

FIG. 5 is a side cross-sectional view of a throat structure 9 andconditioning zone 17 according to another embodiment of this invention.An upwardly extending projection or step member 71 is provided proximateeach of the two opposing ends of the conditioning zone 17 in channel 19,in order to enable the molten glass level 41 to be lowered (e.g. duringmaintenance procedures), such lowering resulting in a level 41 below thetops of members 71 so as to isolate the molten glass in zone 17 fromboth the forehearth and the melter (e.g. molten glass cannot flowtherebetween because it is trapped between the two members 71).

In this embodiment shown in FIG. 5, elongated cylindrical molybdenumtube 11, defining aperture 13 therein, is provided so as to be incommunication with passageway 19 and the interior 15 of vessel 3. Theremainder of the throat structure includes multiple pieces of refractorymaterial 67 which encompass and surround tube 11, as well as supportmember 69 and projections 71 that are provided proximate the outlet sideof tube 11 and proximate the other end of channel 19. Projections 71,due to their locations help isolate the forehearth and melter from theconditioning structure and zone 17. Thus, one can isolate the moltenglass in the conditioner from the melter and forehearth (e.g. when onehas to shut down the system and perform maintenance) by simply loweringthe glass level (from its illustrated position used during normal fiberforming operations) a few inches to a level below the tops ofprojections 71 (e.g. isolate during draining). The top of eachprojection 71 is typically located about 2-3 inches below the normalmolten glass level. It is noted that there is no supplemental heatingenergy provided on or in the conditioner, in certain embodiments.

The conditioning structure 17 further includes a pair of optional burneropenings 73 and an optional needle opening 75 in a top wall thereof (andcorresponding opening in the bottom wall that is not shown). From theillustrated conditioner in FIG. 5, the molten glass batch flows into theforehearth 21, described above. FIG. 6 is a top plan view of the throatand conditioner structure of FIG. 5, illustrating elongated passageway19, optional burner openings 73 which enable the temperature within theconditioner to be maintained at a heightened level so as to keep theglass batch in molten form, optional needle opening 75, and thesurrounding conditioner structure. FIG. 7 is an end view of the FIG. 5-6throat structure, illustrating tube 11 within the surrounding refractory67.

FIG. 8 is a side cross-sectional view of a throat or discharge structure9 according to yet another embodiment of this invention. As illustratedin FIGS. 8-9, this discharge structure 9 includes elongated molybdenumtube 11 defining passageway 13 therein, first refractory member 77 andsecond member refractory 79 surrounding and supporting tube 11, andwater cooling chamber 81 having a water inlet 83 and a similar wateroutlet 84 spaced radially from the inlet. Water is injected throughinlet 83 into annular water cooling cavity 81 in a pressurized manner sothat the water then exits the outlet 84 thereby cooling refractorymembers 77 and 79, as well as tube 11, so as to help elongate their lifespans and prevent corrosion.

Once given the above disclosure, many other features, modifications, andimprovements will become apparent to the skilled artisan. Such otherfeatures, modifications, and improvements are therefore considered to bea part of this invention, the scope of which is to be determined by thefollowing claims.

I claim:
 1. An open top electric melter system for use in the forming ofglass fibers, the open top electric melter system comprising:a melterfor holding and melting glass material therein, said melter including awater cooled shell and a walled structure having a side wall joined atits base to a substantially circular bottom wall thereby to define asubstantially cylindrical electric melter, the walled structure havingan open top so that atmosphere above the glass material is not heatedother than by way of heat emitted from heated glass in said melter;electrical heating means for heating and melting the glass material insaid melter so that a substantial portion of the glass material in themelter is in molten form and a top surface of the glass material in themelter is substantially unmelted and is in quasi-solid or solid form;said electrical heating means being located in said melter so as to bespaced from said side wall and so as to create the highest temperaturein said molten glass in a selected location within said melter above andproximal the center of said substantially circular bottom wall and alower temperature near said side wall; a side-discharge outlet locatedin said side wall of said melter, said outlet permitting molten glassfrom within the melter to flow out of the melter and into a conditioningarea; wherein said side-discharge outlet includes an elongated tubecomprised of a substantially corrosion resistant metal, and having anentrance end and an exit end thereby to define a molten glass flowcommunication path between an interior of the melter and theconditioning area and wherein said entrance end of said tube is solocated as to be spaced from said selected location and proximal thesaid lower temperature near said side wall, whereby said side wall andsaid tube are structured and so located so as to corrode atsubstantially the same rate; and wherein said metal of said tube has arate of corrosion which increases with temperature.
 2. The melter systemof claim 1, wherein said electrical heating means heats the molten glassmaterial in said selected location of the highest temperature of saidmolten glass of the melter to about 3,150°-3,250° F. and near said sidewall to about 2,500°-2,700° F.
 3. The melter system of claim 1 furthercomprising a forehearth, said conditioning area being located betweensaid melter and said forehearth and having an elongated flow channeltherein which extends in glass flow communication between said melterand said forehearth, and wherein said forehearth, said melter, and saidconditioning area are all located on substantially the same level. 4.The melter system of claim 3, further including isolating means disposedbetween said metallic tube and said forehearth, said isolating meansincluding first and second upwardly extending members for allowingisolation of molten glass in the conditioning area from molten glass inthe forehearth and melter.
 5. The melter system of claim 4, furtherincluding means for maintaining the molten glass level at a levelvertically above tops of said upwardly extending members during normalsystem operations, and means for lowering the level to a level below thetops of said upwardly extending members in order to isolate the moltenglass in the conditioning area from molten glass in the forehearth andmelter.
 6. The system of claim 1, wherein said side-discharge outletfurther includes first and second refractory pieces surrounding saidtube, and a liquid-cooled cooling means surrounding said tube and beinglocated adjacent said first and second refractory pieces.
 7. The systemof claim 6, wherein said cooling means includes an annular chambersurrounding said tube, and an inlet and outlet for enabling coolingliquid to circulate to and from said chamber, respectively.
 8. Thesystem of claim 1, wherein said tube is dimensioned so as to causemolten glass to flow out of the melter toward the conditioning zone at arate of from about 13-28 feet per minute.
 9. The system of claim 8,wherein said tube has an inner diameter of from about 1.5-3.0 inches.10. The system of claim 1, wherein the bottom edge of the flow apertureis at least about 2.0 inches above a bottom wall of the melter, and thetop edge of the flow aperture is at least about 2.0 inches below the topunmelted batch surface of the glass material within the melter, duringnormal glass fiber forming operations.
 11. The melter system of claim 1wherein said elongated tube is comprised of molybdenum.
 12. The meltersystem of claim 11 wherein said elongated tube has an inner diameter offrom about 1.5 to 3.0 inches.